Process for preparing grignard compounds



Dec; 29, 1936. H. E. BUC 2,066,198

PROCESS FOR PREPARING GRIGNARD COMPOUNDS I Filed Feb. 26, 1932 l atented Dec. 29, 1 936 i i UNITED STATES PATENT OFFICE Hyym E. Buc, Roselle, N. J., assignor to Standard Oil Development Company, a corporation of Delaware Application February 26, 1932, Serial No. 595,333

9 Claims. (01. 260-11) This invention relates to a new and improved and the temperature may also be controlled by method for preparing metallo organic comregulation of the pressure on the liquid.- The pounds. This invention relates particularly to vapor formed from the control liquid maybe the preparation of magnesium compounds such condensed in suitable external coolers, and the as the alkyl magnesium halides and is of especial condensate returned to tubes 3. Volatile inert application in the synthesis of organic comliquids such as propane, butane, pentane, and the pounds according to the method of Grignard. like, may also be used'for temperature control The Grignard synthesis depends upon the by direct heat exchange. In this event the regupreparation of magnesium organic halides and 'lating liquid, such as butane, may be supplied to the use of these compounds in anhydrous solin admixture with the reagents, and the temvents for the synthesis of various classes of orperature of the condenser may be regulated to ganic compounds such as hydrocarbons, oleflnes, condense and reflux the vapors of this liquid.

P y. secondary nd tert a y al ohols. alde- A solution of an organic halide, such as butyl y ketones, earboxylic acids and the like. chloride, in a suitable solvent, such as ethyl ether,

15 Magnesium compounds suitable for the Grignard is maintained in container t and is supplied synthesis andcontaining aryl and/or alkyl radie through valve 5 and pipe 5', in condenser 6 to eels, magnesium and a halide such as chlorine, the upper portion of reaction zone I. Thisrer min or i din r n r ly rm Grignard agentflows downwardly over themagnesium ando p l These Gr gnard compounds have reacts therewith to form a compound containing sen s a yl and/0r al y y ca o r d ca s and wardly in the solvent through the exit pipe I X usually p e s a a into a receptacle, denoted by receiving vessel 8. The fl synthesis and the Preparation of As it is desirable to maintain the entire system Grien rd mp n are u ally c ndu ted in 'under substantially anhydrous conditions, it is the Presence of anhydrous ethyl ether and preierable that contact with the atmosphere be d t o fo c duct t e Synthesis and the avoided to as great an extent as possible. This rious steps to be used therein have been thoris accomplished in the present apparatus by va- Ollghly described n the eommon'organie C per line 9 which serves to equalize the pressure istry texts and the literature. Other solvents b t en vessels 4 and 8 and to thereby per it a yl ether y be used and the anhydrou the liquidsolvent, carrying reagents and prodt o-e s de e in the c p n i pp ucts, to flow by gravity through condenser 6 ti S o- 575,464 fi d N v r 1931 y and reaction vessel I to receiving vessel 8. If

Willis-n1 Seaman, are especially suitabledesired a plurality of reaction vessels similar to y inventionwill he understood from the I may be connected in series therewith. In this lowing description of the drawing d t case it is preferred to have suitable valves pera p given in connection therewithmitting the shutting oil of each reaction zone The draw n s a d ammati llustration in independently of the others so that it may be sections-1 elevation Of an pp s tab for removed from the system for repacking with onduc in the herein described process. The magnesium and reinsertion into the system.

40 num ral I r p s nts an elongated vertical reao- Valves In, II, I: and is are used for effecting 40 1510B Vessel- This Vessel is filled With magnesium such removal and replacement. The product metal 2 in a finely divided form of large surface may be withdrawn from receptacle 8 by line M, area s 8 P shot, turnihgs and the k or further reactions and syntheses may be con- Th temperehire in s e s nt d by ducted in the receptacle if desired. Additional.

5 cir ulat n liqllid such a Water through tub reagent may be added to the container 4 by line 3 which are means for indirect heat exchange 15. between the reaction zone and the circulated The following example illustrates one means q d; Other means for temperature control of conducting the process covered by this invenmay also be used. For example, the tubes 3 may tion: Magnesium metal in the form of turnings,

be suitably arranged to permit the use of a boilribbon, or very coarse powder is placed'in a tube 50 ing liquid for temperature control, the heat of having means for temperature control such as reaction being removed as latent heat in the heating or cooling'coils distributed therein. An vapor of the control liquid. Liquids of suitable ether solution containing asmall amount of loboiling point, such as butane, methyl bromide, dine or'bromine or an easily reacting metal or ethyl chloride, pentane, and the like, may be used, organic iodide or bromide is trickled through the 55 th general o a Where R I'ep e butyl magnesium chloride which is carried downmagnesium until the magnesium is activated as .sufliciently anhydrous the activation can be effected at normal room temperature in about one half to two hours. Following the activation a solution of an alkyl chloride in ether is passed slowly into the topof the reaction zone. This zone is cooled substantially to room temperature or to any desired temperature depending on the particular halide used, by means of water circulated through the coils. The temperature is thereafter maintained as required by the continued circulation of water through these coils to remove the heat of reaction. A liquid product consisting of a solution of alkyl magnesium chloride in ether and substantially free from any unreacted alkyl chloride is withdrawn from the lower portion of the reaction zone. With n-butyl chloride a yield of 85% of the Grignard reagent is obtained. With isopropyl chloride the yield is about 80 to 85%. The products are suitable for use in the Grignard syntheses according to known methods, or for other purposes.

This process possesses many advantages which are readily discernible over the customary batch processes used for the preparationof Grignard compounds. Losses due to the formation of hydrocarbons by reaction of the Grignard compound with unreacted alkyl halide are almost entirely eliminated since there is always a large excess of magnesium present in the reaction zone and the opportunity for contact of alkyl halide with magnesium alkyl halide is greatly lessened. Alkyl chlorides may be used in this process as readily as the bromides or iodides, whereas ordinarily the use of chlorides involves considerable difliculty and is accompanied by a greatly decreased yield. Hazards due to the volatile nature and inflammable characteristics of the solvents used and the highly exothermic nature of the reaction are greatly lessened since only a very small amount of reagent is present in the reaction zone at any time. The regulation. of the temperature of the reaction zone is also greatly improved with resulting increase in yield of the desired product. The temperature of the reaction zone depends upon the particular reagents used and may be either above or'below room temperature. The reaction zone may accordingly be heated or cooled according to the requisite of each reaction and may be, if desired, coated with heat insulating material. Special high boiling solvents, such as dimethyl aniline, are suitable for use when the metallo organic compounds are to be prepared at elevated temperatures. A smaller amount of solvent is also required. The reaction may be made continuous by using several tubes of mag-' nesium connected in series and/or parallel and by removing, refilling and replacing tubes in which the magnesium is used up during the progress of-the reaction. This method and apparatus are equally applicable to the preparation of other metallo organic halides and metallo organic compounds in gene a! in addition to the Grignard compounds described above. For example, zinc, lead, tin and other metals may be used instead of magnesium.

This invention is not to be limitedto any theory of the reactions described herein, nor to any examples of the process or apparatus which are given solely for purpose of illustration, but only by the following claims in which I wish to claim all novelty insofar as the prior art permits.

I claim:

1. The process for preparing metallo organic compounds which comprises contacting an organic halide of the group consisting of alkyl and aryl halides with a large excess of a metal of the group consisting of magnesium, zinc, lead pounds of the general formula R-Mg-X, where R is an alkyl group and X is a halogen, which comprises feeding an alkyl halide into one part of a reaction zone where said halide is contacted with a large excess of magnesium of a form having large surface area, and removing the resultant alkyl magnesium halide from another part of said reaction zone as fast as formed to avoid contact of unreacted alkyl halide with the alkyl magnesium halide product as far as possible.

3. The process according to claim 2, in which the alkyl halide is fed in ether solution.

4. The process according to claim 2, in which the reaction is initiated by contacting the magnesium with a small amount of an activatorselected from the group consisting of iodine, bromine and easily reacting metal iodides, metal bromides, organic iodides and organic bromides.

5. The process according to claim 2, in which an alkyl chloride is used.

6. Process according to claim 2, carried out at approximately room temperature.

7. Process according to claim 2, carried out in a vertical elongated reaction zone by feedingthe alkyl halide in at the top and withdrawing alkyl magnesium halide at the bottom.

8. Process according to claim 2, carried out continuously by continuously feeding alkyl halide dissolved in a solvent, and continuously separating the solvent from the alkyl magnesium halide product and recycling said solvent with the alkyl halide feed.

9. The process for preparing Grignard compounds which comprises trickling an ether solution of alkyl chloride downwardly through an elongated vertical reaction zone containing a large excess. of finely divided magnesium over the amount of magnesium required to combine with the amount of alkyl halide present in the reaction zone at any particular time, controlling the/temperature in the reaction zone within limits suitable for the production of the particular Grignard compound being prepared and I withdrawing an ether solution of alkyl magnesium chloride from the bottom of said reaction zone as fast as it reaches the bottom.

HYYM E. BUC. 

